Green synthesis of carbon dots from mangosteen peel for fluorescent cancer cells

Recently, carbon dots (CDs) have received significant attention owing to their outstanding optical properties, good solubility, and low toxicity. In this research, CDs were synthesized by a hydrothermal method based on an environmentally friendly and straightforward strategy, using only mangosteen peel and deionized water. The synthesized CDs had an average size of 3.09 ± 0.38 nm. The absorbance spectrum peak for the CDs was seen at 282 nm, and the central wavelength of fluorescence emission was observed at 433 nm under an excitation wavelength of 355 nm. An aqueous solution of CDs exhibited bright green fluorescence when observed with the naked eye under UV irradiation. Both Fourier transform infrared and X-ray photoelectron spectroscope measurements were taken to determine the elemental compositions of the organic substance functional groups on the surface of the CD, such as hydroxyl, carboxyl, and carbonyl groups. These functional groups originate the different emission centers leading to multicolor fluorescent emissions. Furthermore, the synthesized CDs were found to have good biocompatibility with organic and biological materials. The remarkable properties of CDs, including their nanoscale dimensions, strong multicolor fluorescent emissions, non-toxicity, and excellent cell compatibility, could effectively permeate the cell membrane, cytoplasm, and nucleus and provide fluorescence emission. This suggests a significant potential for CDs in fluorescent cell staining applications. Finally, the CDs were used as a fluorescent dye for human colon cancer cells, as they exhibited excellent fluorescence for cell staining.